Generally, the widely-used peripheral input device of a computer system includes for example a mouse device, a keyboard device, a trackball device, or the like. Via the keyboard device, characters or symbols can be inputted into the computer system directly. As a consequence, most users and most manufacturers of input devices pay much attention to the development of keyboard devices. The subject of the present invention is related to a keyboard device.
FIG. 1 is a schematic top view illustrating the outer appearance of a conventional keyboard device. As shown in FIG. 1, plural key structures 10 and 10′ are disposed on a top surface of the conventional keyboard device 1. The key structures 10 have the ordinary sizes. The key structures 10′ are relatively longer. That is, the length of the key structure 10 is slightly larger than the width of the key structure 10, and the length L1 of the key structure 10′ is much larger than the width W1 of the key structure 10′. When one of the key structures 10 and 10′ is depressed by the user's finger, a corresponding key signal is generated to the computer, and thus the computer executes a function corresponding to the depressed key structure. Generally, the user may depress the key structures 10 and 10′ to input corresponding English letters (or symbols) or numbers or execute various functions (e.g., F1-F12 or Delete). For example, the conventional keyboard device 1 is a keyboard for a notebook computer.
The structures of the conventional keyboard device will be illustrated as follows. FIG. 2 is a schematic exploded view illustrating a portion of the conventional keyboard device and taken along a viewpoint. FIG. 3 is a schematic exploded view illustrating a portion of the conventional keyboard device and taken along another viewpoint. Please refer to FIGS. 1, 2 and 3. The conventional keyboard device 1 comprises plural key structures 10 and 10′, a metallic base plate 11 and a membrane circuit board 12. The membrane circuit board 12 comprises plural membrane switches 121 corresponding to the plural key structures 10 and 10′. Each of the plural key structures 10 and 10′ comprises a keycap 101, at least one scissors-type connecting element 102 and a rubbery elastomer 103. The scissors-type connecting element 102 is connected between the keycap 101 and the metallic base plate 11. Moreover, the scissors-type connecting element 102 comprises a first frame 1021 and a second frame 1022. The second frame 1022 is pivotally coupled to the first frame 1021. Consequently, the first frame 1021 and the second frame 1022 can be swung relative to each other. The rubbery elastomer 103 is arranged between the keycap 101 and the metallic base plate 11. Moreover, the rubbery elastomer 103 comprises a contacting part 1031.
While the keycap 101 of any key structure 10 or 10′ is depressed and moved downwardly relative to the metallic base plate 11, the first frame 1021 and the second frame 1022 of the scissors-type connecting element 102 are switched from an open-scissors state to a stacked state. Moreover, as the keycap 101 is moved downwardly to compress the rubbery elastomer 103, the corresponding membrane switch 121 is pushed and triggered by the contacting part 1031 of the rubbery elastomer 103. Consequently, the membrane circuit board 12 generates a corresponding key signal. When the keycap 101 of the key structure 10 or 10′ is no longer depressed, the keycap 101 is moved upwardly relative to the metallic base plate 11 in response to an elastic force of the rubbery elastomer 103. Meanwhile, the first frame 1021 and the second frame 1022 are switched from the stacked state to the open-scissors state again, and the keycap 101 is returned to its original position.
In the keyboard device 1, the key structures 10′ and the key structures 10 are distinguished. As shown in the drawings, the length L1 of the key structure 10′ is much larger than the width W1 of the key structure 10′. Since the length L1 of the keycap 101 of the key structure 10′ is relatively longer, the keycap 101 is readily rocked while the key structure 10′ is depressed. That is, the operating smoothness of the key structure 10′ is adversely affected, and even the tactile feel of the user is impaired. For increasing the operating smoothness of the key structure 10′, the key structure 10′ is further equipped with a special mechanism. For example, the key structure 10′ further comprises a first stabilizer bar 104 and a second stabilizer bar 105. The first stabilizer bar 104 comprises a first linking bar part 1041 and two first hook parts 1042. The two first hook parts 1042 are located at two ends of the first stabilizer bar 104, respectively. The second stabilizer bar 105 comprises a second linking bar part 1051 and two second hook parts 1052. The two second hook parts 1052 are located at two ends of the second stabilizer bar 105, respectively.
The metallic base plate 11 comprises a first connecting structure 111 and a second connecting structure 112. The first connecting structure 111 and the second connecting structure 112 are protruded upwardly, and penetrated through the membrane circuit board 12. The first connecting structure 111 comprises a first locking hole 1111 and a third locking hole 1112. The second connecting structure 112 comprises a second locking hole 1121 and a fourth locking hole 1122. The second locking hole 1121 corresponds to the first locking hole 1111, and the fourth locking hole 1122 corresponds to the third locking hole 1112.
The first linking bar part 1041 of the first stabilizer bar 104 and the second linking bar part 1051 of the second stabilizer bar 105 are pivotally coupled to the keycap 101 of the key structure 10′. The two first hook parts 1042 of the first stabilizer bar 104 are penetrated through the first locking hole 1111 of the first connecting structure 111 and the second locking hole 1121 of the second connecting structure 112, respectively. The two second hook parts 1052 of the second stabilizer bar 105 are penetrated through the third locking hole 1112 of the first connecting structure 111 and the fourth locking hole 1122 of the second connecting structure 112, respectively.
FIG. 4 is a schematic perspective view illustrating a portion of the combination of the metallic base plate and the membrane circuit board of the conventional keyboard device. FIG. 5 schematically illustrates the actions of the first stabilizer bar and the second stabilizer bar of the conventional keyboard device. Please refer to FIGS. 4 and 5. While the keycap 101 of the key structure 10′ is moved upwardly or downwardly relative to the metallic base plate 11, the first stabilizer bar 104 is moved in a first direction D11 or a second direction D12 and rotated in a first rotating direction D13 or a second rotating direction D14. Similarly, the second stabilizer bar 105 is moved in the first direction D11 or the second direction D12 and rotated in the first rotating direction D13 or the second rotating direction D14. By the first stabilizer bar 104 and the second stabilizer bar 105, the key structure 10′ is kept stable and not inclined while the key structure 10′ is moved upwardly or downwardly relative to the metallic base plate 11. Moreover, the uses of the first stabilizer bar 104 and the second stabilizer bar 105 are helpful to increase the strength of the keycap 101.
However, the conventional keyboard device 1 still has some drawbacks. For example, all of the first stabilizer bar 104, the second stabilizer bar 105 and the metallic base plate 11 are made of metallic material. Please refer to FIGS. 4 and 5. While the keycap 101 of the key structure 10′ is moved upwardly or downwardly relative to the metallic base plate 11 and the first stabilizer bar 104 and the second stabilizer bar 105 are correspondingly moved and rotated, the two first hook parts 1042 of the first stabilizer bar 104 and the two second hook parts 1052 of the second stabilizer bar 105 are readily contacted with the metallic base plate 11. While the two first hook parts 1042 and the two second hook parts 1052 collide with the metallic base plate 11, a click sound is generated. Especially when the R corners of the two first hook parts 1042 and the two second hook parts 1052 (e.g., the regions indicated by oblique lines of FIG. 5) collide with the metallic base plate 11, the click sound is generated. This sound is unpleasant noise to the user.
Therefore, there is a need of providing a keyboard device with reduced noise.